ACCUMULATION OF 2 ALKYLATING AGENTS NITROGEN MUSTARD AND BUSULFAN BY MURINE LEUKEMIA CELLS IN VITRO

The accumulation of two alkylating agents by murine leukemia cells in vitro was studied. Nitrogen mustard (HN2) and busulfan rapidly penetrated cells; cell-medium drug distribution ratios of one were established within 3 min at 0° over a wide range of external drug levels. Accumulation of busulfan was not much affected by raising the incubation temperature. NH2 binding was, however, a remarkably temperature-sensitive process. At10-5 M levels, busulfan and HN2 partly inhibited cellular incorporation of precursors into nucleic acids in vitro. When cell types differing widely in sensitivity to these alkylating agents were tested, no differences in capacity for drug accumulation or in subsequent inhibition of nucleic acid synthesis could be found. © 1969.